Centrifugal pump



April 28, 1964 w. F. CHENAULT 3,130,678

CENTRIFUGAL PUMP Filed April 28, 1961 2 Sheets-Sheet l W////am f? C/zenou/z INVENTOR.

ArroR/vlsy April 28, 1964 w. F. CHENAULT 3,130,673

CENTRIFUGAL PUMP Filed April 28, 1961 2 Sheets-Sheet 2 W////0m E C/7e/7o'u/f INVENTOR.

ATTORNEY United States Patent 3,130,678 CENTRIFUGAL PUMP William F. Chenault, 3611 Pecan, Houston, Tex. Filed Apr. 28, 19,61, Ser. No. 107,008 4 Claims. (Cl. 103-103) This invention relates to new types of centrifugal pumps, and more particularlyto centrifugal pumps which are particularly useful for handling liquids containing large solid objects, such as sewage.

This application is a continuation in part of my co pending application of the same title, S.N. 820,322, filed June 15, 1959, now abandoned.

In handling sewage, one of the most vexing problems is pumping of the sewage to disposal plants. Such pumping is sometimes extremely difficult due to the large amount of solid objects which may occur in the sewage. For example, the sewage may contain rags, wooden crates, baskets used in marketing produce, cardboard containers, etc. The usual centrifugal pumps used for handling sewage are easily clogged by these solid objects, and therefore must be frequently dismantled for cleaning.

The use of open impeller pumps, i.e. pumps whose impellers are not shrouded, for handling liquids containing solids, is well known. However, due to the lack of shrouds, these pumps have very low pumping efficiencies.

It is an object of this invention to provide centrifugal pumps which will handle liquids containing large solid objects. It is another object to provide such pumps which will not become clogged by large solid objects. Still an other object is to provide such pumps which have relatively high efiiciency. Yet another object of the invention is to provide centrifugal pumps capable of handling large solid objects at efficiencies substantially equal to the efliciencies of the usual closed or shrouded impeller pumps.

The accomplishment of these and other objects will become apparent hereinafter. According to this invention, centrifugal pumps are provided wherein closed impeller pumping efiiciencies are obtained and, at the same time, adequate clearance for passage of large objects of solid or semi-solid nature through the pumps is provided in new and novel manners.

This result may be accomplished according to this invention in either of two ways, two forms of pumps being herein shown and described. In one form, the pumps have an impeller having an adjustable shroud which cooperates with the impeller to give the high pumping efficiencies and provides adjustable clearance for object passage. In another form, the closed impeller pumping efliciencies are provided by a shrouding effect of the pump housing which is disposed in novel relation to the impeller, and the adjustable object passage spaces are provided by adjustable positioning of the impeller with respect to the housing. In both cases, the shroud or housing is of form to decrease pumping losses at the liquid entrance into the pump housing.

Other objects and advantages of the invention will appear from the following description of preferred embodiments of the invention, reference being made to the accompanying drawings, of which:

FIGURE 1 is a longitudinal sectional view of the fluid end of one form of centrifugal pump according to this invention, the section of the impeller being taken at line 1-1 of FIGURE 2;

FIGURE 2 is a view of the suction face of the impeller used in the centrifugal pump of FIGURE 1, taken at line 22 of FIGURE 1;

FIGURE 3 is a view of the adjustable shroud used in the centrifugal pump of FIGURE 1, taken at-line 3-3 of FIGURE 1 FIGURE 4 is a view similar to FIGURE 1 showing another form of pump according to the invention;

FIGURE 5 is a partial cross section taken at line 5-5 of FIGURE 4; and,

FIGURE 6 is a perspective view of the suction side of the impeller shown in FIGURE 5. i

As shown in FIGURE 1, one form or embodiment of centrifugal pumps of this invention comprises a housing 10 having a suction pipe 12 and a discharge pipe 14. Housing 10 is attached, as by cap screws 16, to a mounting pedestal 18, only part of which is shown. The mounting pedestal has a centrally disposed opening 20 through which a shaft 22 extends. The mounting pedestal is also counterbored at 24 for packing 26 and packing gland 28. Impeller 30 is fitted onto the end of shaft 22 and is secured thereon as by nut 32. Directly opposite the impeller and surrounding the fluid inlet to the housing is adjustable shroud 34.

Between shroud 34 and the front face 36 of housing 10 is a gasket 38. This gasket serves a double purpose. It forms a seal to prevent flow of liquid between shroud 34 and face 36 of housing 10, and it also provides a means for varying the distance between shroud 34 and impeller 30. Shroud 34 and gasket 38 are held in place by bolts 40.

Note that the central opening 42 in shroud 34 is somewhat bell-shaped. This shape, together with the rounding of the inner end 44 of suction pipe 12 forms a substantially smoothly rounded entrance nozzle for the housing. This rounding of the entrance nozzle insures smooth, laminar flow, and avoids the entrance losses generally inherent in an open impeller pump. Furthermore, such design facilitates the passage of solids from the suction pipe into the impeller.

The impeller 30 is shown to have two pumping vanes 46, although it may also be made with one vane or even with three or four vanes if desired for particular applications. Vanes 46 are mounted on a back shroud 48 which has a central hub 50 mounted on shaft 22. When assembled in place, back shroud 50 is positioned so as to leave only a slight clearance, nomore than about 0.010 inch, between the shroud and seal ring 52 which is mounted in the housing behind the impeller.

The thickness of the impeller is such as to fill substantially all the space between seal ring 52 and front shroud 34. However a slight clearance is left between the impeller vanes and the front shroud. The purpose of this clearance is primarily to allow trash, rags, and other like relatively large objects to pass between the vanes and the front shroud without locking of clogging the impeller. As previously indicated, this clearance is adjustable, by means of adding or removing gaskets behind the front shroud 34, or by using gaskets of different thicknesses. The adjustability of this clearance is a distinct advantage, since the clearance may be changed as desiredfor different types and sizes of solids anticipated in the liquid to be pumped. v 7

Another feature of this form of the pumps of this invention which leads to better handling of solids at high efficiencies is the chamfered leading edge 54 of the impeller vanes. Thus at the point of attachment to the back shroud, the vanes extend all the way from the hub to the outer periphery of the impeller, while at their front edge, the vanes do not extend to withinthe diameter of the suction pipe, and therefore provide a wide opening for entry of solid objects into the impeller. Thus the leading edge of the impeller extends from the hub adjacent the back shroudto at least the diameter of the suction pipe at the front face of the impeller.

In operation, liquid containing solid objects is fed into the suction pipe 12 of the pump. Due to the rounded entry formed at 44 and 4-2, the fluid flows smoothly into the housing. Solid objects we not caught and jammed in the impeller, or between the impeller and housing, due to the wide clearances provided between the impeller and front shroud 34, and also due to the ample passage pro vided through the impeller as a result of the chamfering of the leading edge of the impeller vanes. The liquid and solids are then pumped on out discharge pipe 14.

While it has been mentioned that the pumps provided according to this invention will pass rags, wooden crates and baskets of the type used for produce, cardboard eontainers, dirt and sludge, etc., the pumps are particularly useful in cases where rags and rag-like materials occur in the sewage stream. It is peculiar to rag processing plants that the washing equipment thereof, which drains to the sewer system, frequently becomes overloaded with the result that rags in considerable quantities pass into the sewers. The rags, however, will not clog and stop the pumps since the chamfere-d vane surfaces 54 will permit the rags to slide past the vanes and the clearances between the impeller and shroud 34, properly adjusted, will permit the rags to be Worked through to the pump discharge.

Items such as boxes and the like are caused to be disintegrated by the motion of the impeller relative shroud 34 so that they will also pass through the pump without stopping it. However, compressible flexible objects such as rags are more readily passed in this manner, and it is conceivable that excessive quantities of wood could stop the pump while excessive quantities of rags, cardboard, or the like will not do so.

Extremely high efliciencies, approaching those obtained with closed impeller pumps, are obtained with the pump of this invention, due to the provision of the front shroud which provides substantially the same effect as though it were attached to the impeller. The bell-shaped central opening is especially advantageous in obtaining high efiiciencies, due to the low entrance losses resulting from this design. Furthermore, the use of impeller vanes which extend all the way to the hub gives better efiiciency than the use of vanes which extend only in to the diameter of the suction opening.

It is therefore apparent that centrifugal pumps of the FIGURES 1-3 form of this invention are capable of handling liquids containing large solid objects at high efficiencies.

Referring now to the other embodiment of the invention shown in FIGURES 4-6 of the drawings, pump body or housing 61) includes cylindrical tubular liquid entrance conduit 61 provided with a connection flange 62 at its outer end. At its other, or inner, end conduit 61 is integral with the impeller-containing part 64 of the housing. Housing 60 also includes liquid discharge conduit 65 tangential of the inner periphery of the housing part 64.

Opening 67 is provided opposite suction conduit 61 and concentric therewith, opening 67 being large enough to pass impeller 68 therethrough. Around opening 67, circular plate 76 is bolted through its edges to housing 60 by a plurality of bolts 71. Tapped bolt holes are provided in thickened portion 72 of housing 60 around opening 67 for this purpose.

Between portion 72 and plate 70, there is interposed a gasket or spacer 75 of selected thickness, the bolts 71 being received through suitable perforations of the gasket or spacer 75 to hold it in place. The thickness of element 75 determines the degree of spacing between impeller 68 and opposite wall 76 of housing 66* at the suction side of housing 60. The space between wall 76 and the impeller is the space through which solid and other detritus passes in the avoidance of congestion within the pump, and the size of the space is selected depending on the types of detritus which must be passed and on other conditions dependent on the service in which the pump is to be used.

For example, if a pump is to be used for sewage service where objects highly tending to cause pump plugging and/or stoppage are expected to at least sometimes be present in the sewage pumped, then the space between Wall 76 and the impeller will be made relatively larger by increased thickness of gasket or spacer 75. On the other hand, if the service contemplates objects of less plugging and/or stopping tendency, then gasket or spacer 75 may be made thinner and the space between wall 76 and the impeller correspondingly smaller. In all cases, there will be some space, since rubbing of wall 76 and the impeller is to be avoided and since a small space does not reduce pumping efficiency below that of pumps having closed impellers, and will therefore be employed to avoid accidental stoppage or clogging even when such is not normally expected from the nature of the sewage or other liquid to bepumped.

Still referring to FIGURES 4-6 of the drawings, plate 71 will usually be adapted for connection of drive means to the Pump and for provision of a seal at the entrance of shaft 77, which carries impeller 68, into the housing. In the exemplary form of this part of the apparatus shown in the drawings, shaft 77 extends out of the pumping chamber through an opening 80' through plate 70, the opening providing clearance around the hub 81 of impeller 77 which surrounds the shaft within opening 80. Spaced outwardly around opening 80 there is a tubular formation 82 of plate 70 which extends along the shaft to provide a packing space 83. Retainer ring 84, packing 85, and packing pressuring gland 86 provides a seal around the shaft within which the shaft may be rotated by a drive motor (not shown) \operatively connected to the shaft. Formation 82 terminates away from plate 70 in a connection flange 88, or suitable equivalent, for mounting of the pump with the drive motor or with other support means.

Impeller 68 includes the two vanes or blades 90, 91. Each vane 91 91 is longitudinally curved as indicated in FIGURES 5-6. A shroud plate 92 formed integrally with the vanes supports the vanes and provides means for preventing flow at its side of the vanes. At the other side of plate 92 from vanes 91), 91 are four small curved vanes 94 for relieving pressure in the area of the shaft and for preventing entrance of foreign objects to the shaft area. The number of vanes 99, 91 and of vanes 94 may be varied from the numbers of each shown within the scope of this invention.

Shroud 92 is of smaller diameter than opening 67 so that the shroud may be disposed in or partly in the opening.

inwardly of vanes 90, 91 there is a raised area 95 in which there is formed a screw head receiving counterbore 96. Shaft 77 extends through shaft opening 97 through the impeller and screw 98 is screwed into a suitable tapped opening in the shaft end. A key and groove, or the like (not shown), may be provided to prevent impeller rotation relative the shaft.

Still referring to FIGURES 4-6, each of the vanes 90, 91 is concave at both its leading side 1430 and its trailing side 101. An irregularly curved plate-like formation 102 is formed at the part of each vane farthest from plate or shroud 92. Formation 162 of each vane overhangs the remainder of the vane to form a sort of partial shroud at the suction side of each vane. The concave curvatures of vane sides 1%, 1101 provide that the vane sides flare from wall 76 and from plate 92 at each side of each vane. The leading end 193 of each vane is smoothly curved for streamlined flow therepast. The vanes, as shown, curve spirally from near the hub to near the periphery of the impeller. The beveled edge 1436 around the shroud plate 92 helps smooth the outflow of liquids impelled by the vanes, the liquids being discharged from peripheral portion 1W of the pumping chamber through outlet 65.

The pumping efficiency of pumps of the type of Pi URES 4-6 is exceedingly high, being only slightly smaller than the pumping efliciencies of completely shrouded or enclosed impellers. Partial shrouds 102 acting in cooperation with wall 76 spaced therebehind produce this result. Yet at the same time, the clearance between wall 76 and formation 102. permits passage of objects contained in the pumped liquid, the space being adjusted as previously described depending on their nature. The curved and angularly sloped leading edges of the vanes avoid hanging of objects thereon.

Pumps of the FIGURES 4-6 form will usually be more efficient than pumps of the FIGURES l3 form, although the latter will be completely satisfactory in substantially any service in which they might be used.

Referring again to FIGURES 4-6, it will be noted that the suction entrance at 108 is curvingly flared, and this may be altered in curvature to give the flow charac teristics desired. Also, the raised area 95 is smoothly curved to the vane bases to smooth flow thereover, and screw head 98 is rounded and recessed for the same purpose.

While preferred embodiments of the invention have been shown and described, many modifications thereof may be made by a person skilled in the art without departing from the spirit of the inevntion, and it is intended to protect by Letters Patent all forms of the invention falling within the scope of the following claims.

I claim:

1. Centrifugal pump, comprising a pump body having a substantially circular disc-shaped chamber therewithin and an inlet opening centrally of one side of said chamber and an outlet opening tangentially of said chamber, a shaft sealingly and rotatively disposed through a removable wall of said body provided at the opposite side of said chamber from said inlet opening, incompressible spacer means of predetermined thickness at least as great as the largest size of objects carired in the liquid pumped between said body and said removable wall to adjust the extent of said shaft into said chamber, an impeller carried on said shaft within said chamber, said predetermined thickness of said spacer means also fixing the spacing of said impeller at its opposite side from said one side of said chamber consistent with the size of objects carried in the liquid pumped, means for rotating said shaft to rotate said impeller to cause pumping of liquids from said inlet opening to said outlet opening, said fixed spacing of said impeller from said one side of said chamber permitting passage of objects entering said chamber with the liquid from the inlet to the outlet whereby such objects do not clog or stop the pump.

2. Centrifugal pump, comprising a pump body having a substantially circular disc-shaped chamber therewithin and an inlet opening centrally of one side of said chamber and an outlet opening tangentially of said chamber, a shaft sealingly and rotatively disposed through a removable wall of said body provided at the opposite side of said chamber from said inlet opening, an incompressible spacer means of predetermined thickness between said body and said removable wall to adjust the extent of said shaft into said chamber, an impeller carried on said shaft within said chamber, said impeller including a full back shroud, and vanes extending from said back shroud toward said one side of said chamber but spaced therefrom by said spacing depending on the thickness of said spacer means, each said vane being concave along each of its sides and terminating toward said one side of said opening in a separate partial shroud, said partial shrouds cooperating with said one side of said opening to give pumping efficiencies substantially as high as the pumping efiiciencies would be were said partial shrouds a unitary full shroud, said predetermined thickness of said spacer means also fixing the spacing of said impeller from said one side of said chamber consistent with the size of objects carried in the liquid pumped, means for rotating said shaft to rotate said impeller to cause pumping of liquids from said inlet opening to said outlet opening, said fixed spacing of said impeller from said one side of said chamber permitting passage of objects entering said chamber with the liquid from the inlet to the outlet whereby such objects do not clog or stop the pump.

3. Combination of claim 2, the leading ends of said vanes being inclined from said back shroud toward said partial shrouds whereby said objects will not hang thereon.

4. Combination of claim 3, including additional vane means on the opposite side of said back shroud from said first-named vanes to prevent entrance of said objects therebehind and to reduce fluid pressures about said shaft.

References Cited in the file of this patent UNITED STATES PATENTS 640,345 Wilberforce Ian. 2, 1900 1,735,754 Hargis Nov. 12, 1929 1,743,916 Hargis Jan. 14, 1930 1,763,595 Paatcsh June 10, 1930 2,163,464 Llewellyn June 20, 1939 2,272,469 Lannert Feb. 10, 1942 2,353,871 Bowen July 18, 1944 2,438,442 Holt Mar. 23, 1948 2,673,524 Schweizer Mar. 30, 1954 2,779,574 Schneider Jan. 29, 1957 2,910,946 Ask Nov. 3, 1959 FOREIGN PATENTS 97,827 Australia Apr. 15, 1924 285,335 Great Britain Feb. 16, 1928 491,020 Italy Feb. 25, 1954 125,058 Switzerland Mar. 16, 1928 294,450 Switzerland Jan. 16, 1954 

1. CENTRIFUGAL PUMP, COMPRISING A PUMP BODY HAVING A SUBSTANTIALLY CIRCULAR DISC-SHAPED CHAMBER THEREWITHIN AND AN INLET OPENING CENTRALLY OF ONE SIDE OF SAID CHAMBER AND AN OUTLET OPENING TANGENTIALLY OF SAID CHAMBER, A SHAFT SEALINGLY AND ROTATIVELY DISPOSED THROUGH A REMOVABLE WALL OF SAID BODY PROVIDED AT THE OPPOSITE SIDE OF SAID CHAMBER FROM SAID INLET OPENING, INCOMPRESSIBLE SPACER MEANS OF PREDETERMINED THICKNESS AT LEAST AS GREAT AS THE LARGEST SIZE OF OBJECTS CARRIED IN THE LIQUID PUMPED BETWEEN SAID BODY AND SAID REMOVABLE WALL TO ADJUST THE EXTENT OF SAID SHAFT INTO SAID CHAMBER, AN IMPELLER CARRIED ON SAID SHAFT WITHIN SAID CHAMBER, SAID PREDETERMINED THICKNESS OF SAID SPACER MEANS ALSO FIXING THE SPACING OF SAID IMPELLER AT ITS OPPOSITE SIDE FROM SAID ONE SIDE OF SAID CHAMBER CONSISTENT WITH THE SIZE OF OBJECTS CARRIED IN THE LIQUID PUMPED, MEANS FOR ROTATING SAID SHAFT TO ROTATE SAID IMPELLER TO CAUSE PUMPING OF LIQUIDS FROM SAID INLET OPENING TO SAID OUTLET OPENING, SAID FIXED SPACING OF SAID IMPELLER FROM SAID ONE SIDE OF SAID CHAMBER PERMITTING PASSAGE OF OBJECTS ENTERING SAID CHAMBER WITH THE LIQUID FROM THE INLET TO THE OUTLET WHEREBY SUCH OBJECTS DO NOT CLOG OR STOP THE PUMP. 